Operation of an internal combustion engine, for example a diesel, gasoline, or gaseous fuel-powered engine, requires fuel to be supplied to one or more cylinders of the engine and combusted therein to produce power. To ensure efficient engine operation, it is desired that the fuel is supplied to the engine with a predetermined pressure and flow rate.
Combustion of the fuel can generate undesirable emissions. These emissions, which may include particulates, oxides of nitrogen (NOx), and/or oxides of sulfur (SOx), are exhausted to the environment if no emission reduction measures are in place. Many different approaches, such as exhaust aftertreatments, have been developed to reduce the amount of emissions discharged during operation of an engine. Exhaust treatment devices, such as diesel particulate filters and NOx and/or SOx reducing devices, have been used in some exhaust aftertreatment systems.
Some exhaust treatment devices require a fuel supply during normal operations and/or during regeneration events. For example, in some applications, fuel is injected into the exhaust as a reductant for reducing exhaust constituents, such as NOx and/or SOx. In some applications, fuel is supplied to a fuel-fired burner associated with a diesel particulate filter or catalyst and burned in the fuel-fired burner to provide a sufficient temperature for promoting regeneration of the diesel particulate filter or operation of the catalyst.
In addition, in many engine applications, fuel priming is desired before the engine is started for full combustion. Typically, a fuel flow of a predetermined pressure and flow rate is delivered to the engine during a priming event, which may be conducted when the engine is turned off or during a cracking stage at low speeds.
Therefore, a power system that includes an internal combustion engine and an exhaust aftertreatment system may require different fuel flows for different events, such as the engine combustion event, the exhaust aftertreatment event, and the priming event. The pressure and flow rate requirements for these events may also be different.
A fuel system that includes a pump for delivering fuel to multiple devices of an engine system is described in U.S. Patent Application Publication No. 2006/0277899 A1 (the '899 publication) to Ruona published on Dec. 14, 2006. In particular, the '899 publication discloses a fuel system having a mechanical vane transfer and priming pump. The mechanical vane transfer and priming pump delivers fuel to an engine for both combustion and priming, and to an exhaust aftertreatment device for treating exhaust.
While the fuel system of the '899 publication may reduce the complexity of the fuel system by using a single pump for multiple purposes, the fuel system may be problematic. Because the requirements for fuel pressures and flow rates can be different for engine combustion, fuel priming, and exhaust aftertreatment events, the operating conditions (i.e., pressure and flow rate) of the mechanical vane transfer and priming pump may need to be frequently switched between different states (i.e., different pressures and flow rates), which may adversely impact the health of the pump and result in early failure of the pump. Furthermore, the frequent changing of the pump's operating conditions may adversely affect fuel delivery to the engine, thereby reducing engine operation efficiency.
The fuel delivery system of the present disclosure is directed toward improvements in the existing technology.